From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f176.google.com ([209.85.192.176]:33702 "EHLO mail-pf0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753438AbeDVUIM (ORCPT ); Sun, 22 Apr 2018 16:08:12 -0400 Received: by mail-pf0-f176.google.com with SMTP id f15so7475355pfn.0 for ; Sun, 22 Apr 2018 13:08:12 -0700 (PDT) From: Harsh Shandilya To: stable@vger.kernel.org Cc: wangguang , wangguang , Theodore Ts'o , Nathan Chancellor , Harsh Shandilya Subject: [PATCH 3.18.y 2/5] ext4: bugfix for mmaped pages in mpage_release_unused_pages() Date: Mon, 23 Apr 2018 01:37:43 +0530 Message-Id: <20180422200746.29118-3-harsh@prjkt.io> In-Reply-To: <20180422200746.29118-1-harsh@prjkt.io> References: <20180422200746.29118-1-harsh@prjkt.io> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: From: wangguang Commit 4e800c0359d9a53e6bf0ab216954971b2515247f upstream. Pages clear buffers after ext4 delayed block allocation failed, However, it does not clean its pte_dirty flag. if the pages unmap ,in cording to the pte_dirty , unmap_page_range may try to call __set_page_dirty, which may lead to the bugon at mpage_prepare_extent_to_map:head = page_buffers(page);. This patch just call clear_page_dirty_for_io to clean pte_dirty at mpage_release_unused_pages for pages mmaped. Steps to reproduce the bug: （1） mmap a file in ext4 addr = (char *)mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); memset(addr, 'i', 4096); （2） return EIO at ext4_writepages->mpage_map_and_submit_extent->mpage_map_one_extent which causes this log message to be print: ext4_msg(sb, KERN_CRIT, "Delayed block allocation failed for " "inode %lu at logical offset %llu with" " max blocks %u with error %d", inode->i_ino, (unsigned long long)map->m_lblk, (unsigned)map->m_len, -err); (3）Unmap the addr cause warning at __set_page_dirty:WARN_ON_ONCE(warn && !PageUptodate(page)); (4) wait for a minute,then bugon happen. Cc: stable@vger.kernel.org Signed-off-by: wangguang Signed-off-by: Theodore Ts'o [@nathanchance: Resolved conflict from lack of 09cbfeaf1a5a6] Signed-off-by: Nathan Chancellor Signed-off-by: Harsh Shandilya --- fs/ext4/inode.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 859af265ae1b..e7f75942aea5 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1338,6 +1338,8 @@ static void mpage_release_unused_pages(struct mpage_da_data *mpd, BUG_ON(!PageLocked(page)); BUG_ON(PageWriteback(page)); if (invalidate) { + if (page_mapped(page)) + clear_page_dirty_for_io(page); block_invalidatepage(page, 0, PAGE_CACHE_SIZE); ClearPageUptodate(page); } -- 2.15.0.2308.g658a28aa74af